Authorities are still trying to determine what caused the explosion, which forced 60 firefighters and Department of Environmental Protection officials to respond to the bio-diesel fuel processing plant on Passaic Street around 3:40 p.m., according to Newark Fire Chief Michael Lalor.

The victim, who was not identified, suffered third-degree burns to eighteen percent of his body and was taken to Saint Barnabas Medical Center’s burn unit in Livingston with non-life threatening injuries, Lalor said.

The man was apparently connecting hoses to a tanker truck filled with methanol when the acid container burst behind him, according to Lalor. He said the facility mixes acids and other chemicals to make bio-diesel fuels.

Firefighters and DEP representatives spent nearly 21/2 hours trying to decontaminate the building. Lalor said 100 to 200 gallons of acid spilled and flooded the structure, and hazmat teams weren’t able to fully neutralize the acid in the area until 6:10 p.m.

Methanol and sulfuric acid are flammable substances, according to Lalor, and officials on the scene had to work quickly to close the methanol container after the acid leak, fearing a possible second explosion.

"It has a low flash point, but we wanted to make sure it didn’t ignite at all," Lalor said.

The incident also forced State Police to shut down water traffic in the nearby Passaic River for about an hour, as firefighters worked to dissipate a vapor cloud that was floating toward the river as a result of the acid explosion.